(a) Field of the Invention
The present invention relates to a nanophosphor sheet and a backlight device.
(b) Description of the Related Art
Display devices are classified into emissive display devices that emit light on their own to illuminate an image and non-emissive display devices that use light from a separate light source to display an image. An example of non-emissive display devices is liquid crystal display.
Liquid crystal display is currently one of the most widely used flat panel displays, and includes two display panels on which field generating electrodes such as a pixel electrode and a common electrode are formed, a liquid crystal layer interposed therebetween, and a backlight device providing light to the display panels holding the liquid crystal layer. A liquid crystal display displays an image by applying a voltage to the field generating electrode to generate an electric field on the liquid crystal layer, determining the direction of liquid crystal molecules of the liquid crystal layer therethrough, and controlling the magnitude of light provided by the backlight device. A typically backlight device includes a light source emitting light, a light guide plate dispersing light emitted from the light source to convert light into a planar light source, various kinds of diffusion films, and the like.
Cold cathode fluorescent lamp (CCFL), external electrode fluorescent lamp (EEFL), and light emitting diode (LED) are some of the light sources that have been used for the backlight device.
A liquid crystal display adopting a color filter may generate white light by mixing blue light emitted from a light emitting diode (LED) chip and yellow light absorbing a portion of blue light to perform excitation and emission. In this case, a yellow phosphor is formed in a dispersion state in a sealing layer applied on a chip to display yellow light.
However, there is a problem in that degradation of the phosphor occurs due to heat generated in the light emitting diode (LED).
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.